Insulator



FIG. 1 is a rear perspective view of an insulator showing our design;

FIG. 2 is a front perspective thereof;

FIG. 3 is a top view thereof;

FIG. 4 is a bottom view thereof;

FIG. 5 is a first side view thereof;

FIG. 6 is a second side view thereof;

FIG. 7 is a front view thereof; and,

FIG. 8 is a rear view thereof.

The broken lines represent portions of the insulator that form no part of the claimed design. 

CLAIM The ornamental design for an insulator, as shown and described. 